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Description/Abstract

One of the most important assumptions in most multispectral image transformation methods is that the position of the dark endmember is placed at the origin of the n-D spectral feature space regardless of the target spectral signature. A series of field experiments under varying illumination resulted that ‘shadowlines’, which hypothetically pass through the dark endmember, never pass directly through the origin of the spectral feature space. A conceptual radiative transfer model was derived and demonstrated its susceptibility to the proportion of scattered light from the sky. The model showed that the location of the dark endmember, defined as the 'dark point virtual endmember (DPVE)’, is assumed to be sensitive to the state of atmosphere. Further analysis also revealed that the DPVE plays an important role in defining the data distribution in spectral feature space. This study suggested that accurate estimation of DPVE could enable to reduce some of the uncertainties associated with conventional dark point atmospheric correction methods.